Employee Benefit Plans (AOCI and regulatory assets and liabilities that have not been recognized as components of periodic benefit (credit) cost) (Detail) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss		$ 1,793	$ 1,700
Dominion Energy Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss		187	169
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss		3,327	3,477
Prior service (credit) cost		5	7
Total	[1]	3,332	3,484
Pension Benefits | Dominion Energy Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss		150	555
Prior service (credit) cost		0	0
Total	[2]	150	555
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss		241	350
Prior service (credit) cost		(339)	(393)
Total	[1]	(98)	(43)
Other Postretirement Benefits | Dominion Energy Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss		44	89
Prior service (credit) cost		(49)	(52)
Total	[2]	$ (5)	$ 37

[1] As of December 31, 2019, of the $3.3 billion and $(98) million related to pension benefits and other postretirement benefits, $2.0 billion and $(65) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities. As of December 31, 2018, of the $3.5 billion and $(43) million related to pension benefits and other postretirement benefits, $2.0 billion and $(41) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities.

[2] As of December 31, 2019, of the $150 million related to pension benefits, $147 million is included in AOCI, with the remainder included in regulatory assets and liabilities; the $(5) million related to other postretirement benefits is included entirely in regulatory assets and liabilities. As of December 31, 2018, of the $555 million related to pension benefits, $200 million is included in AOCI, with the remainder included in regulatory assets and liabilities; the $37 million related to other postretirement benefits is included entirely in regulatory assets and liabilities.